Southward was promoted from the practice squad Friday.
After Daeshon Hall (knee) was sent to injured reserve, a roster spot opened up. Since safeties Demetrious Cox (ankle) and Kurt Coleman (knee) are listed as out for Sunday's game against the Lions, bringing up a safety was an easy choice. Southward will slot in as the No. 4 safety and likely won't see many defensive snaps, if any, but he'll be deployed in special teams situations.